“I’ve been working my whole life on climate change. And now, because of policies to fight local air pollution, Chinese carbon emissions will peak and begin to decline in less than ten years, and our efforts on climate change will have nothing to do with it.”

That was the message from one of several Chinese scholars, businesspeople, NGO staff, and officials I met over the last week in Beijing and Shanghai. One focus of my discussions was China’s massive air pollution problem: How, I asked people from a range of backgrounds, would China clean up the mess?

The answer matters to non-Chinese observers not only because of its consequences for Chinese political stability but because China’s choices could have a big impact on global greenhouse gas emissions. Install scrubbers on coal-fired power plants to cut local air pollution and you do nothing to reduce carbon dioxide emissions. (You actually increase them a nudge.) Ditto if you simply move polluting industries away from the big cities. Switch to lower-carbon energy, though, and you get a twofer: reduced local air pollution and lower carbon emissions too.

So I was heartened – and quite frankly surprised – to hear so consistently that people expect switching from coal to gas (along with penetration of zero-carbon energy) to not only be at the core of the Chinese strategy to reduce local air pollution (not really news) but to actually be fairly successful.

What’s the reasoning behind this? The big Chinese air pollution problem has to do with fine particulate matter, known as PM2.5. A lot of that comes from coal-fired power plants that could, in principle, have their emissions scrubbed. But it has been challenging to get companies to turn on their scrubbers even when it’s been possible to get them installed. And much of the coal use comes from heavy industry, where scrubbing emissions isn’t an option. That leaves two other choices: switch heavy industry from coal to gas or move it inland. (A third option – shut it down – is already being employed in some cases where there’s overcapacity and the politics are manageable.) Moving industry can entail political and economic problems; in particular, without adequate infrastructure, it can become unmanageably expensive to move industrial products from inland to places where they’re used. Nonetheless, industry will often move. So I was encouraged to hear optimism that even relocated industry would become more efficient, and often switch fuels, at least partly cleaning up.

This all leaves one very large question: where will China get its gas from? Some will be imported – news last week that China and Russia have signed a massive gas supply deal may be at best mixed news from a geopolitical perspective, but it augurs well for climate change. In particular, it suggests that Chinese wariness about energy security is increasingly being outweighed by worries about air pollution, a theme that I also heard frequently. (Of course, there were other factors driving the China-Russia deal too.) Other gas will be domestic. The massive unknown here is how much of this domestic gas will be conventional or shale gas and how much will be synthetic gas ("syngas") produced from coal. The first two are good for climate change; syngas, in contrast, is not.

Alas, on that last question, the people I talked to were all over the map, with estimates of anywhere from one to one-hundred billion cubic meters a year of syngas in the next decade. That – along with the more basic question of how well China is able to execute on its strategy – will determine how much Chinese efforts to combat air pollution translate into leverage on climate change. I’m not ready yet to place my bet alongside the climate researcher who now believes that Chinese carbon emissions will peak as a byproduct of efforts to fight local air pollution. But the fact that such a prospect can even be taken seriously is welcome news.